1. Field of the Invention
The present invention relates to a communication device and a communication method.
2. Description of the Related Art
In the past, signal deterioration was known to occur due to inter symbol interference (ISI) or the like of a digital signal in high-speed serial communication. The ISI is a phenomenon in which a difference occurs in a signal amplitude of a receiving side between a signal pattern in which logical inversion frequently occurs and a signal pattern in which the same logic continues.
As a countermeasure against the ISI, a method of relatively emphasizing a signal level when logical conversion occurs is generally used. Further, in order to restore a signal waveform changed due to the characteristics of a transmission path or minimize a change in the signal waveform, an equalizer is provided to adjust a reception signal.
For example, Japanese Patent Application Laid-open No. 2010-245616 discloses an equalizer parameter setting device that determines an equalizer parameter based on the detected characteristics of a receiver.
Further, Japanese Patent Application Laid-open No. 2011-130231 discloses a parameter setting device that determines a signal intensity parameter, a signal amplitude parameter, and an equalizer parameter based on a predetermined determination criterion and the detected characteristics of a receiver.
Furthermore, Japanese Patent Application Laid-open No. 2007-243802 discloses an equalizer control device that sets a filter parameter value in an equalizer performing waveform correction on an electric signal converted from an optical signal.
However, when an optical signal is used in a part of a communication path, a change in the amplitude of an electric signal is deleted in ON and OFF of a light-emitting component indicating digital signals in spite of the fact that the amplitude of the electric signal is changed and equalizing is performed. Therefore, there is a problem that an equalizing signal superimposed on a transmitting side disappears and is not received on a receiving side, and thus signal deterioration may not be reduced.
It is desirable to provide a communication device and a communication method capable of reducing signal deterioration, even when an optical signal is used in a part of a communication path.